Filters which separate out particulate matter from liquids, as well as liquid contaminants, are well-known in the industry. Such filters are particularly useful for diesel fuel, where water is removed from the diesel fuel passing through the filter to increase the combustion efficiency of the engine. Such fuel filters are also useful with gasoline, oil and other liquid fuels.
A number of such filters include cup-shaped collection bowls located below the filter media to collect the liquid contaminants. U.S. Pat. Nos. 4,626,348; 4,692,245; 4,740,299; 4,668,393; 4,997,555; 5,244,571; and 5,622,623 for example, all show and describe such filters, whereby a collection bowl with a threaded upper end is removably connected to the housing or casing of a filter cartridge. The filter cartridge includes a ring of appropriate filtration media bounded by upper and lower end caps. Particles in the fuel flowing through the filter media are separated out in the media, while the liquid contaminants collect on the surface of the media, and drop down into the attached collection bowl. The collection bowl is transparent to allow monitoring of the liquid level and includes a drain to allow removal of the liquid contaminants when appropriate.
As shown in U.S. Pat. No. 5,622,623, one technique for attaching the collection bowl to the cartridge is to include a ring-shaped member supported by a radially in-turned portion of the cartridge casing, where the ring-shaped member includes an annular portion with radially-outward directed threads. The collection bowl, with radially inward directed threads, is then easily screwed onto or off of the filter member. Radial flow passages in the ring-shaped member fluidly connect a peripheral cavity in the casing, that is, between the casing and the outer surface of the filter media, with the attached collection bowl, such that liquid contaminants can pass radially-inward through the passages and then downwardly into the attached collection bowl.
U.S. Pat. No. 4,740,299 shows a similar structure, whereby the ring-shaped member has radially-inward directed threads, and the collection bowl has radially-outward directed threads.
In some instances, the casing of the filter cartridge is designed to be spun onto a filter head, and includes an upper tap plate with a series of peripheral openings fluidly connected with the peripheral cavity, and a central opening fluidly connected with the central cavity of the element. The openings direct fluid into and out of the filter.
The above filters have received widespread acceptance in the marketplace as providing reliable, efficient devices for separating particles and liquid contaminants from fuel. Unfortunately, one of the limitations of some of the above filters is that the filter cartridge cannot be removed from the casing of the filter. This requires the entire filter cartridge and casing to be disposed of when the media is spent, which can raise environmental issues. The collection bowl is typically the only re-usable component as it can be screwed onto and off of the cartridge when the cartridge is replaced.
On the other hand, providing a filter where the cartridge can be easily removed from the casing also raises issues. For example, it is possible that an end user or repair person can forget to install or re-install a fresh cartridge, and thereby operate the engine without proper filtration. It can also be confusing as to the correct type of filter cartridge used in the filter, and a user or repair person may attempt to install an incorrect cartridge in the casing. This can all have a serious effect on the operation of the internal combustion engine.
Thus, it is believed there is a demand in the industry for a filter including a filter cartridge and attached collection bowl, whereby the filter cartridge is removable from the filter casing but where the filter cannot be assembled or used without a proper filter cartridge installed.
It is also believed there is a continual demand for new and unique filters with removable collection bowls which are easy and cost-effective to manufacture and assembly and provide efficient separation of particles and liquid contaminants in fuel flowing through the filter.